Current mobile or computer devices use a variety of different navigation mechanisms including trackball devices, multi-click joysticks and capacitance based touch pads. However, there may be problems associated with each of these. Trackballs and joysticks can be unreliable and relatively expensive to implement. In addition, capacitance based touch pads do not operate well if the finger is covered, for example, by a glove, and their size can be large in relation to the devices, such as mobile phones and PDAs.
Optical navigation devices may also operate on the same principles as optical mice by comparing successive frames of an area image. However, typical devices use light emitting diode (LED) light sources that may require collimation and imaging optics and may add thickness to the devices. There is therefore a desire to provide an optical navigation device which has a reduced thickness compared to typical devices and which operates in a safe manner. In addition, it is desirable that such a device be manufactured in a simple manner and with a low part count.